1. Field of the Invention
The present invention relates generally to offering a location information service, and more particularly, to a system and method capable of providing location information using mobile codes, without using radio signals for positioning (or position measurement), such as Global Positioning System (GPS) signals.
2. Description of the Related Art
Mobile communication systems have evolved to provide not only voice services but also a variety of additional services differentiated from the voice services. Profits of communication service providers that provide only the voice services have already been limited by market saturation. Therefore, the communication service providers are seeking new profit opportunities by providing a variety of additional services differentiated from the voice services, such as, Location Based Service (LBS) services, which are based on location information of Mobile Stations (MSs). LBS services provide user-requested additional application services by combining location information of moving users or vehicles with a variety of other information in real time. Therefore, acquisition of the location information is one of the important factors in providing the LBS services. Originally, LBS services were used by large distribution companies to track their vehicles and their freights. Recently, however, LBS services are being extended to include services for the general public, such as Find-a-Person, Real-Time Traffic Information, Weather Information at a user's current location, etc.
The location information is the contents of locations of actual geographical features and objects on the surface of the earth, which are represented using a predetermined method such as a Global Positioning System (GPS) scheme and a network scheme that provides location information of MSs. In the GPS scheme, a radio navigation system for measuring accurate positions, velocities and times of objects on the surface of the earth using satellites, measures arrival times of waves by receiving satellite signals transmitted from the satellites, and calculates locations of users based on the measured times. The network scheme provides location information of MSs using Base Stations (BSs) and/or Relay Stations (RSs) in Code Division Multiple Access (CDMA) communication systems or Global System for Mobile communication (GSM) communication systems.
FIG. 1 is a diagram illustrating an example of providing an LBS service by acquiring location information using the conventional GPS scheme and the conventional network scheme.
Referring to FIG. 1, in order to acquire desired location information, an MS with a built-in GPS module can determine a distance between satellites and its user by calculating arrival times of signals transmitted from the satellites, and an MS without a built-in GPS module can provide an LBS service based upon the Cell Identifications (Cell-IDs) of cells managed by BSs or RSs currently serving the MS. In order to acquire more detailed and precise location information, triangulation may be performed using signals transmitted from three or more BSs or RSs.
However, the GPS-based and network-based location schemes can only provide limited personal location information. GPS-based location information can be precisely calculated, but this precise information is limited to MSs with a GPS function, which requires GPS hardware. Further, the GPS scheme is unavailable within in a room or a building. In addition, because an accuracy of the network-based location information falls within several hundred meters through several kilometers due to a difference between a user and BSs or RSs in terms of the time and radio signals, accurate location information of the user or a service such as path guidance cannot be provided, and therefore, accuracy of the network scheme is subject to significant changes depending on the location of the user.
Therefore, there is a need for a technology capable of providing location information services by extracting precise location information without using measurement values calculated by radio signals for position measurement.